Orthodontic treatment of improperly positioned teeth involves the application of mechanical forces to urge the teeth into correct alignment. The most common form of treatment involves use of orthodontic brackets which are small slotted bodies configured for direct cemented attachment to the front (labial) or rear (lingual) surfaces of the teeth, or alternatively for attachment to bands which are in turn cemented or otherwise secured around the teeth.
A resilient curved arch wire is seated in the bracket slots, and the arch wire is bent or twisted before installation so the restoring force exerted by the seated resilient wire tends to shift the teeth into correct alignment. Depending on the shape of the arch wire (both round and rectangular cross sections are in common use) and the orientation of the bracket slot, it is possible to apply forces which will shift, rotate or tip the teeth in any desired direction.
Conventional orthodontic brackets include tie wings around which small ligature wires are tied to hold the arch wire in a securely seated position in the brackets. Ligatures or some other form of fastening means are essential to insure that the activated arch wire is properly positioned around the dental arch, and to prevent the wire from being dislodged from the bracket slots during chewing of food, brushing of the teeth, or application of other forces to the wire by the patient.
During one or more stages of an overall orthodontic treatment program, it is often desirable to use auxiliary appliances to supplement or replace the corrective force supplied by the arch wire. Metal springs or elastic bands or threads are typical auxiliary devices used for this purpose, and they must be anchored at their ends to spaced-apart brackets to apply the desired restoring force to the teeth.
Auxiliary-appliance anchorage is usually provided by welding or soldering a wire hook, cleat, button, or eyelet to a bracket or directly to the arch wire. Installation of this kind of anchor is time consuming for the orthodontist, and, with the exception of crimpable anchors, usually must be fitted prior to installation of brackets and arch wires on the patient's teeth.
Another style of anchor is a special ligature which is a U-shaped hairpin-like length of ligature wire having generally parallel legs which are welded together close to the base of the "U" configuration to form a small closed loop in which an auxiliary appliance can be hooked. This ligature is as time consuming to install as a conventional ligature wire, and has the usual twisted and severed tail which must be carefully tucked against the bracket to avoid tissue contact and irritation.
The ring of this invention is in retrospect a very simple structure which provides hook and eyelet anchorage for an auxiliary appliance, and can also serve as a clean, nonirritating ligature to secure the arch wire to the bracket. The ring is a continuous loop of stainless-steel wire dimensioned to fit over the bracket tie wings. When so fitted, the ring is quickly and easily twisted to be tightened against the bracket, and to provide a smooth (no sharp ends) tail which is bent to form the desired hook or eyelet anchorage.